Conventionally, an electric vehicle is equipped with high-voltage batteries delivering a DC current to an inverter which transforms this DC current into an AC current making it possible to power an electric motor, the latter ensuring the movement of the vehicle.
So as to ensure the recharging of these high-voltage batteries, it is known to equip the vehicle with an embedded charging device mainly comprising an AC/DC converter making it possible to rectify the AC power from the electrical network to charge the batteries. The device also advantageously comprises a DC-DC converter adapting the network voltage level to that of the batteries.
The electronic components of the power supply subsystem on the one hand and of the charging subsystem on the other hand are costly. Moreover, the powering of the motor and the charging of the batteries are performed with different phases, so it has been proposed, in the applications EP 0 603 778 and WO97/08009, to reuse a part of the motor and of the components used to power it to implement the battery charging device.
To this end, the battery charging device uses the inverter to form an AC-DC converter and the windings of the motor to form the inductances. The switchover from the motor power supply mode to the battery charging mode is handled by switching means with power contactors by disconnecting the neutral.
The use of power connectors is, however, problematical in the sense that, because they carry current for the electric machine, they have to be overengineered. To overcome this drawback, one solution consists in producing a structure having integrated switching means with H-shaped bridges.
However, in the two abovementioned cases, the use of the phases of the motor as inductance for rectifying the current of the electrical network causes disturbances on the rotor of the motor. In practice, the inductances are magnetized by the alternating currents, thus creating magnetic fields. These magnetic fields act on the rotor which may start to move, for example by vibrating, and even, depending on the magnetic fields and characteristics of the rotor, start rotating. This setting in motion poses problems with regard to both comfort and safety in the case of a use of the combined electric device in an electric vehicle, even if the latter may be equipped with a system for decoupling the axle system from the machine during charging.